39 



when taken, but a short exposure to the atmosphere re- 

 vived them. 



The effect of cold on the larvae of this species furn- 

 ishes something of interest. For eleven days after Jan. 

 10, '93 the daily minimum temperature ranged from 2° 

 to 17° below zero. Larvae exposed practically without 

 protection, during this period were not injured. Larvae 

 placed in water and frozen for the period of a week were 

 ninjured. Larvae broken in two while frozen were cap- 

 able of movement when thawed at the expiration of a 

 week. I have seen it stated that insects would be killed 

 if crystals of ice were formed inside of them, but this 

 one is an exception to the rule, as dozens of specimens 

 which I examined were filled with crystals, and pieces 

 and whole ones were alive when the temperature was 

 raised above the freezing point. 



In a number of articles in the Canadian Ento- 

 mologist for 1883, 1888, 1889 are discussed, to some 

 length, the hibernating habits of the larvae of obliquata. 

 The difference in observation recorded in these articles 

 seems to have originated from the hibernaculum which 

 this species evidently chooses according to circum- 

 stances. Out of five contributors, two have observed 

 the larvae to hibernate in earth decayed wood or under- 

 bark, one observed them only in the stems of, Typha 

 latifola their food plant, and two found them in all the 

 above situations. According to my own observations, 

 the larvae will pass to the pupa state under any circum- 

 stances — with or without protection. Here, it is prob- 

 able that it is not particular in choosing a place to 

 hibernate. In almost every case I have observed that, 

 naturally, the larva passes the winter in the stems of 

 its food plant, and pubatates there during the first 

 warm days of spring. 



